This is the time of year when there is a lot of traffic on the gardening blogs from people who have heard good things about Three Sisters Gardening. They want to try it, even though they are not sure of what it is exactly, and how to do it.
Essentially, the Three Sisters Garden is a companion planting of corn, pole beans and vining winter squash. The corn seed is sowed first, and when it breaks ground and grows beans seeds are sowed around the stocks. Then, when the beans break ground, the squash seed is sowed. The idea is that the pole bean vines use the corn stocks for support and the leaves of the winter squash plant shade out and suppress weeds, and minimize water loss through evaporation.
Many people believe that they can plant Three Sisters and pick fresh corn and beans as they become available. They can, but I do not believe that was the original intent of the companion planting, and that there are some difficulties; the most obvious of which is that in order to get close enough to pick the corn and beans you need to step on the squash.
Depending on the blog, the origin of the Three Sisters is Iroquois, Mohawk or Cherokee Indian; so I feel safe saving that it is Native American. This suggests to me that the Three Sisters were planted for fall harvest and winter storage. I just think they were more concerned about having something to eat over winter and winter squash, dried corn and beans was the solution.
So as a source of fresh produce, I would not recommend incorporating this into your vegetable garden; but it is a good gardening experiment and great cultural, historic and learning opportunity; something to do with your children. So, here is my version of the Three Sisters.
First prepare the planting beds (at least 5×7-feet per bed) by incorporating as much organic matter as you can. Mother Nature is supposed to provide the water and, if you are trying this as a school project, you probably will not be stopping by during the summer to water the plants. The organic matter will retain moisture and provide some nutrients to the plants. I would also incorporate some 10-10-10 fertilizer, since it is easier and less expensive than burying fish under the corn seed.
Next sow the corn in a 1-foot grid. The plan is to have 4 rows with 6 plants per row. Corn is pollinated by the wind. The pollen in the tassels has to contact each of the silk hairs coming out of the corn husk. Each of the silk hairs is attached to a corn kernel, gridding the corn ensures more kernels are pollinated. The time to sow is when the soil temperature is mid-fifty degrees, as soon as the beds are prepared. For authenticity, try to plant an Indian Ornamental like Smoke Signal or Seneca Red Stalker, or a Popping Corn.
When the corn is at least four inches high, sow the pole beans 6-inches apart between each stock. Leave one lane across the row between plants 3 and 4 open. I think Cherokee Trail of Tears, Rattlesnake and October all have Native American lineages.
As soon as the beans come up, sow three winter squash seeds across the north side of the bed, and the open lane. Here you might want to try Buttercup, Hubbard or Delicata.
Once the squash begins to vine out, you may have to intervene and direct them between the rows and not up the stocks. Other than that, the sisters should take care of each other. Let the corn and beans dry on their plants. Leave the squash until the first frost before harvesting.